By way of Chris Chapman, it has come to my attention that a significant num=
ber of readers of this list-serve are
misinformed concerning the nature and performance of the VolksMeter seismog=
raph.  Even though the gravitational pendulum
in the VolksMeter has a period of only about 1 second, that doesn't mean th=
e instrument is limited to sensing only local
earthquakes, as with conventional short-period seismometers.  Several Volks=
Meters around the world--such as mine here at
Mercer University, or Michael Phillips' seismograph at the Edward Pigot Sei=
smic Observatory near Coonabarabran,
Australia--routinely pick up the surface waves from teleseismic events.  Th=
e outstanding broadband performance of the
VolksMeter that allows these measurements, involves two novel features: (i)=
 the unique sensor of fully-differential
capacitive type that allows pendulum deflection measurements (position rath=
er than velocity) all the way from 10 Hz down
to d.c., and (ii) the outstanding electronics that was developed by Larry C=
ochrane to work with this sensor.  Operation
is by means of WinSDR and WinQuake, and the heart of the system is the Anal=
og Devices AD7745 capacitance to digital (24
bit) converter.  As such, the VolksMeter is the first "fully-digital" seism=
ograph--because the sensor, along with the
support electronics for data storage and communication, is completely digit=
al (excepting the moving electrodes that are
attached to the pendulum).  Commercial seismographs still use analog electr=
onics to measure changes in a capacitive
sensor of lower symmetry and reduced sensitivity compared to the sensor of =
the VolksMeter.  They use a separate analog
to digital converter to provide data storage capability and uplinks to the =
web.  Operation of these commercial
instruments is further complicated by the challenges of force feedback need=
ed to maintain stable performance, free from
the problems of mechanical creep.  By comparison, a gravitational pendulum =
can be made nearly immune to mechanical
instabilities, without using the complicated electronics of feedback. In ge=
neral, sensitivity of an instrument can be
increased by either of two means--(i) using less-sophisticated electronics,=
 but operating with a mechanical system made
highly sensitive by period lengthening, or (ii) by working with a much more=
 stable, shorter period instrument in the
form of a gravitational pendulum, that is supported by superior electronics=
..  The former requires genius of the type
that was exhibited by Gunar Streckeisen in the building of instruments like=
 the STS-1 and 2.  The latter requires a
genius in circuit development, in the person of someone like Larry Cochrane=
, to create a state of the art electronics
package for seismic use--the very package that is resident in the VolksMete=
r.  Because there are significantly different
seismic instruments that are described by the term, I am being here careful=
 to associate the adjective 'gravitational' with the
word pendulum.  Unlike these other instruments, where the oscillating membe=
r is also called a 'pendulum', the equilibrium
direction of a gravitational pendulum (in the absence of acceleration or ti=
lt influence) is that of a plumb bob
(direction of the earth's gravitational field).  A detailed description of =
the physics of such instruments is provided in
my article titled "Tutorial on gravitational pendulum theory applied to sei=
smic sensing of translation and rotation",
Bulletin of the Seismological Society of America, Vol. 99, No. 2B, (2009).
By way of Chris =
Chapman, it has come to my attention that a significant number of readers o=
f this list-serve are 
misinformed conce=
rning the nature and performance of the VolksMeter seismograph.  Even =
though the gravitational pendulum 
in th=
e VolksMeter has a period of only about 1 second, that doesn't mean the ins=
trument is limited to sensing only local 
earthquakes, as with conventional short-period seismometers.  Severa=
l VolksMeters around the world--such as mine here at 
Mercer University, or Michael Phillips' seismograph at the Ed=
ward Pigot Seismic Observatory near Coonabarabran, 
Australia--routinely pick up the surface waves from teleseismi=
c events.  The outstanding broadband performance of the 
VolksMeter that allows these measurements, involves t=
wo novel features: (i) the unique sensor of fully-differential <=
/p>
capacitive type that allows pendulum deflection mea=
surements (position rather than velocity) all the way from 10 Hz down =
to d.c., and (ii) the outstanding electronic=
s that was developed by Larry Cochrane to work with this sensor.  Oper=
ation 
is by means of WinSDR and WinQuak=
e, and the heart of the system is the Analog Devices AD7745 capacitance to =
digital (24 
bit) converter.  As su=
ch, the VolksMeter is the first "fully-digital" seismograph--beca=
use the sensor, along with the 
support =
electronics for data storage and communication, is completely digital (exce=
pting the moving electrodes that are 
at=
tached to the pendulum).  Commercial seismographs still use analog ele=
ctronics to measure changes in a capacitive 
sensor of lower symmetry and reduced sensitivity compared to the senso=
r of the VolksMeter.  They use a separate analog 
to digital converter to provide data storage capability and =
uplinks to the web.  Operation of these commercial 
instruments is further complicated by the challenges of fo=
rce feedback needed to maintain stable performance, free from 
the problems of mechanical creep.  By compariso=
n, a gravitational pendulum can be made nearly immune to mechanical 
instabilities, without using the complicated e=
lectronics of feedback. In general, sensitivity of an instrument can be 
increased by either of two means--(i) usin=
g less-sophisticated electronics, but operating with a mechanical system ma=
de 
highly sensitive by period lengtheni=
ng, or (ii) by working with a much more stable, shorter period instrument i=
n the 
form of a gravitational pendulum,=
 that is supported by superior electronics.  The former requires geniu=
s of the type 
that was exhibited by Gun=
ar Streckeisen in the building of instruments like the STS-1 and 2.  T=
he latter requires a 
genius in circuit =
development, in the person of someone like Larry Cochrane, to create a stat=
e of the art electronics 
package for se=
ismic use--the very package that is resident in the VolksMeter.  Becau=
se there are significantly different 
se=
ismic instruments that are described by the term, I am being here careful t=
o associate the adjective 'gravitational' with the 
word pendulum.  Unlike these other instruments, where the=
 oscillating member is also called a 'pendulum', the equilibrium 
direction of a gravitational pendulum (in the abs=
ence of acceleration or tilt influence) is that of a plumb bob <=
/p>
(direction of the earth's gravitational field). &nb=
sp;A detailed description of the physics of such instruments is provided in=
 
my article titled "Tutorial on gr=
avitational pendulum theory applied to seismic sensing of translation and r=
otation", 
Bulletin of the Seismolo=
gical Society of America, Vol. 99, No. 2B, (2009).
=